Author Archives: R-B

Mobile Sun-seeker for indoor planters

Indoor plants are great for adding some greenery to home interior decoration. Most of the time low-lighting conditions can sustain indoor plants. However, it is still important that they get proper sunlight for healthy and greenish growth. If you have windows in more than one direction of your house, it is possible that the sunniest spot inside your house is not always the same during the course of day. This mobile sun-seeker robot helps to navigate the interior plants to enjoy the sunniest spot in the house.

The mobile sun-seeker uses two continuous rotation servos to move around and are controlled by an Arduino nano board. Two 6V solar panels are used in two opposite sides of plant to detect the incident sunlight. The sum of the two solar cell readings is used to compute the overall sunniness of a particular location. The sun-seeker robot also uses two ultrasonic range detectors to avoid running into other objects or falling off the edges.

Mobile sun-seeker robot

Mobile sun-seeker robot

 

Arduino pin monitor shield

Carsten Tonn-Petersen has designed this Arduino pin monitor and tester shield to assist his prototyping work with Arduino. The key features of this shield is it provides one LED for every single I/O pin and can be used with Arduino Uno, Leonardo, Mega, Due, and Mini. The shield also features one tact switch and one toggle switch for digital inputs along with two potentiometers for simulating analog input voltages during prototyping.

Arduino tester shield

Arduino tester shield

The complete list of features as Carsten has mentioned about his Arduino pin monitor and tester shield are listed below:

  • One LED for every single input or output
  • Can be used with Uno, Leonardo, Mega, Due, Mini, etc.
  • Also fits with my universal I/O board
  • Power taken from Arduino 5V and 3.3V outputs, and the Vin
  • Load on any pin is 10 kohm or more
  • LED intensity proportionally reflects the pin voltage or duty cycle
  • Builtin inputs and outputs for testing new ideas:
    • One pushbutton (P) to digital input
    • One toggle switch (T) to digital input
    • Two potentiometers (1, 2) to two analog inputs
    • 4 digital outputs to 7-segment number display (e.g. for program STATE output)
    • Very small moving coil voltmeter on PWM output
    • Piezo loudspeaker on PWM output
    • 4 digital outputs to open-drain MOSFET (builtin flyback diodes)
    • One opto-isolated digital input
    • One opto-isolated digital output (not for 230 VAC)
    • One direct analog input via miniature LEMO coax connector
    • One direct digital I/O/PWM via miniature LEMO coax connector
    • One reed-relay (no coil) to digital input
    • One mercury shake alarm to digital input
    • One TMP36 temperature sensor to analog input
    • One electret microphone to analog input (x 100 gain)
    • One NTC resistor to analog input (linearized)
    • One light-dependant resistor to analog input
  • All inputs and outputs can be made passive to enable inputs from other sources
  • LED’s grouped in 16 for analog I/O, 14 for digital I/O/PWM, 8 for digital I/O/Tx/Rx and 32 digital I/O. In total 70 LEDs.
  • All LEDs are very high efficiency white SMD types with coloured film on top, according to the group.
  • The LEDs cathode reference can be adjusted down to -2V: LEDs will start to light up when pin voltage goes positive.
  • The cathode reference is divided into one for analog and one for digital, adjusted individually
  • Maximum input voltages can be selected between 5V or 3.3V to fit with DUE board
  • Voltage for internal circuits and steppermotor outputs can be selected between 5V and Vin
  • IC-sockets and Arduino pins are all gold plated
  • LEMO I/O, Shake-sensor, NTC, TMP36, microphone and piezo-speaker are in a detachable separate module

Visit Carsten’s project page for more details.

Alphanumeric LED display for web data

This 8-character alphanumeric LED display project connects to an USB port of PC and can display any data from your computer or from web such as weather info, RSS feeds from your favorite websites, time, and anything else that you would like to. The display has 8 push button for user interface to quickly navigate through various functionalities. A PC application developed in C# is used to configure the display. The display uses the PIC18F4550 microcontroller and its firmware is developed using MPLAB IDE using C18 compiler.

Alphanumeric LED display for web info

Alphanumeric LED display for web info

Visit the author’s page for schematics, software, and other details.

Raspberry Pi FM transmitter

Do you know you can make your Raspberry Pi play your favorite music over an FM radio with a very little effort? Yes, all you need to make this FM radio transmitter is a Raspberry Pi, an SD card, a power supply, and a small piece of wire to serve as antenna. You can load your audio files into the SD card and choose your transmission frequency in the commercial FM band. The PirateRadio.py python script generates frequency-modulated radio waves on the Raspberry Pi GPIO pin 4, which are injected into air with a short wire connected to it.

Raspberry Pi FM transmitter

Raspberry Pi FM transmitter

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